926 J. A. POLLOCK, E. M. WELLISCH AND A. B. B. RANCLAUD, 
and the make of the circuit. The measurements are given 
in Figures 5, 6, and 7, the currents previous to the break 
of the circuit being marked on the curves. The observa- 
tions were interlocked, with reference to change of carbons, 
so the curves are comparable. 
Fig. 6. 
s ot make of circuit in Volts. 
IW CLAP 
| |! a 
/nterval Peay Lreak ee make or oireule if Seconds. 
Potential difference between Carbon 
A comparison of the relations given in Figures 5, 6, and 
7, shows that the characteristic bend in the curves is more 
pronounced the higher the previous current. Greater 
currents mean larger masses of heated carbon with con- 
sequent higher temperatures for equal intervals between 
the break and the make of the circuit. It is also seen that 
the greater the arc length the higher the potential differ- 
ence at which the characteristic bend occurs. 
